A lithographic apparatus is a machine that applies a desired pattern onto a substrate or part of a substrate. A lithographic apparatus may be used, for example, in the manufacture of flat panel displays, integrated circuits (ICs) and other structures involving fine features. In a conventional apparatus, a patterning device, which may be referred to as a mask or a reticle, may be used to generate, for example, a circuit pattern corresponding to an individual layer of a flat panel display (or other structure). This pattern may be transferred on (part of) the substrate (e.g. a glass plate), e.g. via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate.
Instead of a circuit pattern, the patterning device may be used to generate other patterns, for example a color filter pattern, or a matrix of dots. Instead of a mask, the patterning device may comprise a plurality of individually controllable elements (e.g. in the form of an array). An advantage of such a system compared to a mask-based system is that the pattern can be changed more quickly and for less cost.
Existing processes for fabricating semiconductor or other devices are usually based on a sequence of steps which involve the creation of layers and/or areas with different electrical properties on or within a substrate. As is known in the art, one of the most frequently used processes for fabricating such devices is the photolithography process. In a commercial environment, photolithographic processes often involve the exposure of substrates with a patterned beam of radiation in order to create patterns on those substrates. In order to create a patterned radiation beam, a radiation beam is transmitted through or reflected off a mask or reticle provided with a fixed pattern.
A problem associated with existing photolithography processes is the fixed nature of the pattern provided by the mask or reticle. A fixed pattern provided by the mask or reticle is not changeable without changing the mask or reticle to one provided with another fixed pattern.